Multilayer ceramic capacitor and manufacturing method of multilayer ceramic capacitor

ABSTRACT

A multilayer ceramic capacitor includes: a multilayer structure in which each of a plurality of ceramic dielectric layers and each of a plurality of internal electrode layers are alternately stacked, wherein: (a current value at 10 V/μm when a direct voltage is applied to the plurality of the ceramic dielectric layers at 125 degrees C.)/(a current value at 10 V/μm when a direct voltage is applied to the plurality of the ceramic dielectric layers at 85 degrees C.) is more than 5 and less than 20; and a donor element concentration in the plurality of ceramic dielectric layers is 0.05 atm % or more and 0.3 atm % or less.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2017-027330, filed on Feb. 16,2017, the entire contents of which are incorporated herein by reference.

FIELD

A certain aspect of the present invention relates to a multilayerceramic capacitor and a manufacturing method of a multilayer ceramiccapacitor.

BACKGROUND

A thickness of a dielectric layer is being reduced because downsizingand enhancement of a capacitance of a multilayer ceramic capacitor aredemanded. As a result, electric field intensity applied to thedielectric layer increases. Thereby, life property of the dielectriclayer is degraded. And so, it is proposed that a donor element such asMo (molybdenum), W (tungsten) or the like is added to a dielectric layerin order to improve life property (for example, see Japanese PatentApplication Publications No. 2016-139720 and No. 2016-127120).

SUMMARY OF THE INVENTION

However, in the technologies, a position of the donor element in thedielectric layer is not defined. When the donor element exists in acrystal grain of main component ceramic of the dielectric layer, thedonor element contributes to the life property of the dielectric layer.A donor element existing in a crystal boundary does not contribute tothe life property of the dielectric layer. Therefore, even if aconcentration of the donor element of a whole of the dielectric layer isdefined, preferable life property is not achieved.

The present invention has a purpose of providing a multilayer ceramiccapacitor and a manufacturing method of the multilayer ceramic capacitorthat are capable of achieving preferable life property of a dielectriclayer.

According to an aspect of the present invention, there is provided amultilayer ceramic capacitor including: a multilayer structure in whicheach of a plurality of ceramic dielectric layers and each of a pluralityof internal electrode layers are alternately stacked, wherein: (acurrent value at 10 V/μm when a direct voltage is applied to theplurality of the ceramic dielectric layers at 125 degrees C.)/(a currentvalue at 10 V/μm when a direct voltage is applied to the plurality ofthe ceramic dielectric layers at 85 degrees C.) is more than 5 and lessthan 20; and a donor element concentration in the plurality of ceramicdielectric layers is 0.05 atm % or more and 0.3 atm % or less.

According to another aspect of the present invention, there is provideda manufacturing method of a multilayer ceramic capacitor including:forming a green sheet of which a concentration of a donor element withrespect to a main component ceramic is 0.05 atm % or more and 0.3 atm %or less; forming a multilayer structure by alternately stacking thegreen sheet and a conductive paste for forming an internal electrode;and baking the multilayer structure, wherein the multilayer structure issintered in the baking so that, in the multilayer structure after thebaking, (a current value at 10 V/μm when a direct voltage is applied tothe plurality of the ceramic dielectric layers at 125 degrees C.)/(acurrent value at 10 V/μm when a direct voltage is applied to theplurality of the ceramic dielectric layers at 85 degrees C.) becomesmore than 5 and less than 20.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a partial perspective view of a multilayer ceramiccapacitor;

FIG. 2 illustrates a flowchart of a manufacturing method of a multilayerceramic capacitor;

FIG. 3A and FIG. 3B illustrate a relationship between temperature changecoefficients (125 degrees C./85 degrees C.) and accelerated life valuesof examples 1 to 5 and comparative examples 1 and 2.

FIG. 4 illustrates a relationship among a temperature change, a leakcurrent value and an applied voltage of a multilayer ceramic capacitorof a comparative example 1;

FIG. 5 illustrates a relationship among a temperature change, a leakcurrent value and an applied voltage of a multilayer ceramic capacitorof an example 1; and

FIG. 6 illustrates a relationship among a temperature change, a leakcurrent value and an applied voltage of a multilayer ceramic capacitorof an example 4.

DETAILED DESCRIPTION

A description will be given of an embodiment with reference to theaccompanying drawings.

Embodiment

FIG. 1 illustrates a partial perspective view of a multilayer ceramiccapacitor 100 in accordance with an embodiment. As illustrated in FIG.1, the multilayer ceramic capacitor 100 includes a multilayer chip 10having a rectangular parallelepiped shape, and a pair of externalelectrodes 20 a and 20 b that are respectively provided at two edgefaces of the multilayer chip 10 facing each other. In four faces otherthan the two edge faces of the multilayer chip 10, two faces other thanan upper face and a lower face of the multilayer chip 10 in a stackingdirection are referred to as side faces. The external electrodes 20 aand 20 b extend to the upper face, the lower face and the two sidefaces. However, the external electrodes 20 a and 20 b are spaced fromeach other.

The multilayer chip 10 has a structure designed to have dielectriclayers 11 and internal electrode layers 12 alternately stacked. Thedielectric layer 11 includes ceramic material acting as a dielectricmaterial. The internal electrode layers 12 include a base metalmaterial. End edges of the internal electrode layers 12 are alternatelyexposed to a first edge face of the multilayer chip 10 and a second edgeface of the multilayer chip 10 that is different from the first edgeface. In the embodiment, the first face faces with the second face. Theexternal electrode 20 a is provided on the first edge face. The externalelectrode 20 b is provided on the second edge face. Thus, the internalelectrode layers 12 are alternately conducted to the external electrode20 a and the external electrode 20 b. Thus, the multilayer ceramiccapacitor 100 has a structure in which a plurality of dielectric layers11 are stacked and each two of the dielectric layers 11 sandwich theinternal electrode layer 12. In the multilayer chip 10, the internalelectrode layer 12 is positioned at an outermost layer. The upper faceand the lower face of the multilayer chip 10 that are the internalelectrode layers 12 are covered by cover layers 13. A main component ofthe cover layer 13 is a ceramic material. For example, a main componentof the cover layer 13 is the same as that of the dielectric layer 11.

For example, the multilayer ceramic capacitor 100 may have a length of0.2 mm, a width of 0.125 mm and a height of 0.125 mm. The multilayerceramic capacitor 100 may have a length of 0.4 mm, a width of 0.2 mm anda height of 0.2 mm. The multilayer ceramic capacitor 100 may have alength of 0.6 mm, a width of 0.3 mm and a height of 0.3 mm. Themultilayer ceramic capacitor 100 may have a length of 1.0 mm, a width of0.5 mm and a height of 0.5 mm. The multilayer ceramic capacitor 100 mayhave a length of 3.2 mm, a width of 1.6 mm and a height of 1.6 mm. Themultilayer ceramic capacitor 100 may have a length of 4.5 mm, a width of3.2 mm and a height of 2.5 mm. However, the size of the multilayerceramic capacitor 100 is not limited.

A main component of the internal electrode layers 12 is a base metalsuch as nickel (Ni), copper (Cu), tin (Sn) or the like. The internalelectrode layers 12 may be made of a noble metal such as platinum (Pt),palladium (Pd), silver (Ag), gold (Au) or alloy thereof. The dielectriclayers 11 are mainly composed of a ceramic material that is expressed bya general formula ABO₃ and has a perovskite structure. The perovskitestructure includes ABO_(3-α) having an off-stoichiometric composition.For example, the ceramic material is such as BaTiO₃ (barium titanate),CaZrO₃ (calcium zirconate), CaTiO₃ (calcium titanate), SrTiO₃ (strontiumtitanate), Ba_(1-x-y)Ca_(x)Sr_(y)Ti_(1-z)Zr_(z)O₃ (0≤x≤1, 0≤y≤1, 0≤z≤1)having a perovskite structure. For example, the dielectric layer 11 hasa thickness of 1 μm or less or a thickness of 0.8 μm or less.

The dielectric layer 11 includes a donor element. The donor element isan element that can be replaced with an A site of the perovskite ABO₃and can become an ion of which valence is three (a part of rare earthelements such as Y (yttrium), La (lanthanum), Sm (samarium), Gd(gadolinium), Dy (dysprosium) or Ho (Holmium)) or an element that can bereplaced with a B site of the perovskite ABO₃ and can become ion ofwhich valence is five or more (a part of transition metals such as V(vanadium), Mo (molybdenum), Nb (niobium), W (tungsten) or Ta(tantalum)). For example, when the main component ceramic of thedielectric layer 11 is a perovskite, V (vanadium), Mo, Nb, La, Ta or thelike can be used as the donor element. When the dielectric layer 11includes a donor element, generation of an oxygen defect can besuppressed. Therefore, life property of the dielectric layer 11 isimproved. When the donor element concentration of the dielectric layer11 is excessively low, it may not be possible to achieve the effect ofthe donor element sufficiently. And so, in the embodiment, theconcentration of the donor element in the dielectric layer 11 is 0.05atm % or more. On the other hand, when the donor element concentrationof the dielectric layer 11 is excessively high, insulating property maybe degraded or the bias property may be degraded in accordance withsolid-solution of the donor element. And so, in the embodiment, thedonor element concentration in the dielectric layer 11 is 0.3 atm % orless. “atm %” means a concentration “atm %” of the donor element on thepresumption that the B site is 100 atm %.

The main component ceramic of the dielectric layer 11 is not structuredwith a single crystal grain but includes a plurality of crystal grains.Therefore, the donor element may be equally dispersed in crystal grainsand crystal grain boundaries or may be mainly dispersed in the crystalgrain boundaries. When the donor element exists in the crystal grains ofthe main component ceramic, the donor element suppresses the oxygendefect. Therefore, even if the donor element concentration in thedielectric layer 11 is 0.05 atm % or more and 0.3 atm % or less, thedonor element does not always contribute to the life property of thedielectric layer 11.

When a temperature increases, electrons are excited to a conduction bandin accordance with a donor level of the donor element. In this case, aleak current also increases. When temperature dependence of the leakcurrent is large, the donor element exists in the dielectric layer 11and is solid-solved in crystal grains of the main component ceramic.Therefore, when a temperature change coefficient of the leak current islarge, the donor element contributes to the life property of thedielectric layer 11. And so, the embodiment focuses on a temperaturechange coefficient of a leak current.

In concrete, (a current value at 10 V/μm when a direct voltage isapplied to the dielectric layer 11 at 125 degrees C.)/(a current valueat 10 V/μm when a direct voltage is applied to the dielectric layer 11at 85 degrees C.) is used as the temperature change coefficient of theleak current. In the following, the temperature change coefficient isreferred to as a temperature change coefficient (125 degrees C./85degrees C.).

When the temperature change coefficient (125 degrees C./85 degrees C.)is small, an amount of the donor element in the main component ceramicgrains of the dielectric layer 11 is small. In this case, maybe,preferable life property of the dielectric layer 11 is not achieved. Andso, the temperature change coefficient (125 degrees C./85 degrees C.) isincreased to more than a predetermined value. On the other hand, whenthe temperature change coefficient (125 degrees C./85 degrees C.) islarge, the amount of the donor element in the main component ceramicgrains of the dielectric layer 11 is large. In this case, insulatingproperty and bias property of the dielectric layer 11 may be degraded.And so, the temperature change coefficient (125 degrees C./85 degreesC.) is decreased to less than a predetermined value. In the embodiment,the temperature change coefficient (125 degrees C./85 degrees C.) ismore than 5 and less than 20. It is therefore possible to suppress theleak current and improve the life property. And, it is preferable thatthe temperature change coefficient (125 degrees C./85 degrees C.) ismore than 6 and less than 15.

It is possible to calculate the temperature change coefficient bychanging an ambient temperature with use of a thermostatic chamber,applying a direct voltage of 10 V/μm between the external electrode 20 aand the external electrode 20 b, and measuring a leak current after 60seconds after the applying.

It is preferable that at least a part of the dielectric layer 11 inwhich a voltage difference occurs has preferable life property.Therefore, at least a part of the dielectric layer 11 having anelectrical capacity of the multilayer ceramic capacitor 100 haspreferable life property. And so, the dielectric layer 11 in a region inwhich the internal electrode layer 12 connected to the externalelectrode 20 a faces with the internal electrode layer 12 connected tothe external electrode 20 b includes a donor element of whichconcentration is 0.05 atm % or more and 0.3 atm % or less, and hasproperty of 5<the temperature change coefficient (125 degrees C./85degrees C.)<20.

When an average grain diameter of the main component ceramic of thedielectric layer 11 is small, a dielectric constant becomes smaller.And, maybe, a preferable electrostatic capacitance is not achieved. Andso, it is preferable that an average grain diameter of the maincomponent ceramic of the dielectric layer 11 is 80 nm or more. On theother hand, when the average grain diameter of the main componentceramic of the dielectric layer 11 is large, an area of grain boundariesacting as a movement barrier of oxygen defects is reduced in thedielectric layer 11 having a thickness of 1 μm or less and the lifeproperty may be degraded. And so, it is preferable that the averagegrain diameter of the main component ceramic of the dielectric layer 11is 200 nm or less. The grain diameters are Feret diameters that aremeasured by adjusting a scale factor so that a single image of ascanning electron microscope or a transmission electron microscopeincludes 80 to 150 crystal grains, capturing a plurality of images sothat a total number of the crystal grains is 400 or more, and measuringall Feret diameters of all of the crystal grains on the images. Theaverage grain diameter is an average of the Feret diameters.

Next, a description will be given of a manufacturing method of themultilayer ceramic capacitor 100. FIG. 2 illustrates a manufacturingmethod of the multilayer ceramic capacitor 100.

(Making process of raw material powder) A ceramic material powder isprepared as a main component of the dielectric layer 11. A donor elementmay be included in the dielectric layer 11 by mixing a ceramic materialand a donor element source. However, it is preferable that a ceramicmaterial in which a donor element is solid-solved in advance is used.When the donor element is Mo, Mo compound such as MoO₃ may be used asthe donor element source.

Next, additive compound may be added to ceramic powder material, inaccordance with purposes. The additive compound may be an oxide of Mg(magnesium), Mn (manganese), V (vanadium), Cr (chromium) or a rare earthelement (Y (yttrium), Dy (dysprosium), Tm (thulium), Ho (holmium), Tb(terbium), Yb (ytterbium), Sm (samarium), Eu (europium), Gd (gadolinium)and Er (erbium)), or an oxide of Co (cobalt), Ni (nickel), Li (lithium),B (boron), Na (sodium), K (potassium) and Si (silicon), or glass. Forexample, compound including additive compound is added to a ceramicmaterial powder and is calcined. Next, the resulting ceramic materialgrains are wet-blended with additive compound, is dried and is crushed.Thus, the ceramic material powder is prepared.

(Stacking Process) Next, a binder such as polyvinyl butyral (PVB) resin,an organic solvent such as ethanol or toluene, and a plasticizer such asdioctyl phthalate (DOP) are added to the resulting ceramic materialpowder and wet-blended. With use of the resulting slurry, a strip-shapeddielectric green sheet with a thickness of 0.8 μm or less is coated on abase material by, for example, a die coater method or a doctor blademethod, and then dried.

Then, a pattern of the internal electrode layer 12 is provided on thesurface of the dielectric green sheet by printing a conductive paste forforming the internal electrode with use of screen printing or gravureprinting. The conductive paste includes powder of the main componentmetal of the internal electrode layer 12, a binder, a solvent, andadditives as needed. It is preferable that the binder and the solventare different from those of the above-mentioned ceramic slurry. As aco-material, the ceramic material that is the main component of thedielectric layer 11 may be distributed in the conductive paste.

Then, the dielectric green sheet on which the internal electrode layerpattern is printed is stamped into a predetermined size, and apredetermined number (for example, 200 to 500) of stamped dielectricgreen sheets are stacked while the base material is peeled so that theinternal electrode layers 12 and the dielectric layers 11 are alternatedwith each other and the end edges of the internal electrode layers 12are alternately exposed to both edge faces in the length direction ofthe dielectric layer so as to be alternately led out to a pair ofexternal electrodes of different polarizations.

Cover sheets, which are to be the cover layers 13, are compressed on thestacked green sheets and under the stacked sheets. The resulting compactis cut into a predetermined size (for example, 1.0 mm×0.5 mm). Thus, aceramic multilayer structure having a rectangular parallelepiped shapeis obtained.

(Baking process) Next, after removing the binder in N₂ atmosphere at 250degrees C. to 500 degrees C., the resulting ceramic multilayer structureis baked for ten minutes to 2 hours in a reductive atmosphere in atemperature range of 1100 degrees C. to 1300 degrees C. Thus, eachcompound structuring the dielectric green sheet is sintered. In thismanner, a sintered structure having the multilayer chip 10 having themultilayer structure in which the sintered dielectric layers 11 and thesintered internal electrode layers 12 are alternately stacked and havingthe cover layers 13 formed as outermost layers of the multilayer chip 10in the stack direction is obtained.

(Re-oxidizing process) After that, a re-oxidizing process may beperformed at 600 degrees C. to 1000 degrees C. in N₂ gas atmosphere.

EXAMPLES Example 1

In an example 1, barium titanate was used as the main component ceramicof the dielectric layer 11. Mo was used as the donor element. MoO₃ wasadded to the main component ceramic powder so that Mo is 0.2 atm % on apresumption that Ti of the main component ceramic powder is 100 atm %.The resulting main component ceramic powder was sufficiently wet-blendedand crushed with a ball mil. Thus, the dielectric material was obtained.An organic binder and a solvent were added to the dielectric material.And dielectric green sheets were made by a doctor blade method. Theorganic binder was polyvinyl butyral (PVB) resin or the like. Thesolvent was ethanol, toluene or the like. And a plasticizer and so onwere added. Next, the conductive paste for forming the internalelectrode layer 12 was made by mixing powder acting as a main componentmetal of the internal electrode layer 12, a binder, a solvent and anadditive as needed. The organic binder and the solvent were differentfrom those of the dielectric green sheet. The conductive paste wasscreen-printed on the dielectric sheet. 500 of the dielectric greensheets on which the conductive paste for forming the internal electrodelayer were stacked, and cover sheets were stacked on the stackeddielectric green sheets and under the stacked dielectric green sheets.After that, a ceramic multilayer structure was obtained by a thermalcompressing. And the ceramic multilayer structure was cut into apredetermined size. The thickness of the dielectric layer 11 after thebaking was 0.8 μm.

Example 2

In an example 2, a main component ceramic powder in which 0.05 atm % ofMo was solid-solved in advance was used as the dielectric material. A Mosource was not added to the main component ceramic powder. Otherconditions were the same as those of the example 1.

Example 3

In an example 3, a main component ceramic powder in which 0.1 atm % ofMo was solid-solved in advance was used as the dielectric material. A Mosource was not added to the main component ceramic powder. Otherconditions were the same as those of the example 1.

Example 4

In an example 4, a main component ceramic powder in which 0.2 atm % ofMo was solid-solved in advance was used as the dielectric material. A Mosource was not added to the main component ceramic powder. Otherconditions were the same as those of the example 1.

Example 5

In an example 5, a main component ceramic powder in which 0.3 atm % ofMo was solid-solved in advance was used as the dielectric material. A Mosource was not added to the main component ceramic powder. Otherconditions were the same as those of the example 1.

Comparative Example 1

In a comparative example 1, a Mo source was not added to a maincomponent ceramic powder. Other condition were the same as those of theexample 1.

Comparative Example 2

In a comparative example 2, a main component ceramic powder in which0.35 atm % of Mo was solid-solved in advance was used as the dielectricmaterial. A Mo source was not added to the main component ceramicpowder. Other conditions were the same as those of the example 1.

(Analysis) FIG. 3A illustrates a relationship between temperature changecoefficients (125 degrees C./85 degrees C.) and accelerated life valuesof the examples 1 to 5 and the comparative examples 1 and 2. In FIG. 3A,the accelerated life values are expressed as MTTF (Mean Time ToFailure). The accelerated life value was measured by applying a directvoltage of 10 V between the external electrode 20 a and the externalelectrode 20 b at 125 degrees C., measuring a leak current value with anampere meter, and measuring a time to a dielectric breakdown. The meantime to failure is an average of times to the dielectric breakdown of 20numbers of the multilayer ceramic capacitors.

As illustrated in FIG. 3A, a correlation occurs between the temperaturechange coefficient (125 degrees C./85 degrees C.) and the acceleratedlife values. In the comparative example 1 in which a donor element wasnot added (barium titanate in which Mo was not added), the temperaturechange coefficient (125 degrees C./85 degrees C.) was approximately 2that was a small value. And the accelerated life value was 200 min orless that was a small value. Therefore, a preferable life value was notachieved. In the example 1 (barium titanate in which Mo was added) inwhich the main component ceramic powder and the Mo source were mixedwith each other and were baked, the temperature change coefficient (125degrees C./85 degrees C.) was approximately 5 that was a relativelylarge value. The accelerated life value was approximately 200 min to 300min that was a long life property. In the examples 2 to 5 (bariumtitanate in which Mo was solid-solved) in which the main componentceramic powder in which Mo was solid-solved in advance was sintered, thetemperature change coefficient (125 degrees C./85 degrees C.) was 7 to20 that was a larger value than that of the example 1. The acceleratedlife value was approximately 200 min to 1200 min that was a larger valuethan that of the example 1. However, when the temperature changecoefficient (125 degrees C./85 degrees C.) was more than 20 as in thecase of the example 2, the leak current value at 85 degrees C. increasedby two orders or more with respect to the barium titanate in which Mowas not added, as illustrated in FIG. 3B.

From the results, it is demonstrated that when the donor elementconcentration in the dielectric layer 11 is 0.05 atm % to 0.3 atm % andthe temperature change coefficient (125 degrees C./85 degrees C.) ismore than 5 and less than 20, it is possible to suppress the leakcurrent and it is possible to improve the life property.

FIG. 4 illustrates a relationship among a temperature change, a leakcurrent value and an applied voltage of the multilayer ceramic capacitor100 of the comparative example 1. As illustrated in FIG. 4, when a donorelement was not added to the dielectric layer 11, there was littlechanging of the leak current value with respect to the temperature. Itis thought that this is because a donor element was not solid-solved incrystal grains of the main component ceramic of the dielectric layer 11.

FIG. 5 illustrates a relationship among a temperature change, a leakcurrent value and an applied voltage in the multilayer ceramic capacitor100 of the example 1. As illustrated in FIG. 5, when a donor element wasadded to the dielectric layer 11, a temperature change appears in theleak current value. It is thought this because a part of donor elementswere solid-solved in crystal grains of the main component ceramic of thedielectric layer 11.

FIG. 6 illustrates a relationship among a temperature change, a leakcurrent value and an applied voltage in the multilayer ceramic capacitor100 of the example 4. A total added amount of Mo in the dielectric layer11 in the example 1 was the same as that in the example 4. However, asillustrated in FIG. 6, the changing of the leak current value withrespect to the temperature became larger than FIG. 5. It is thought thatthis is because the barium titanate in which a donor element wassolid-solved in advance was used, and a lot of donor elements exist incrystal grains of the main component ceramic of the dielectric layer 11.From the results of FIG. 4 to FIG. 6, it is demonstrated that when themain component ceramic powder in which a donor element was solid-solvedin advance was used, a lot of donor elements exist in crystal grains.

Although the embodiments of the present invention have been described indetail, it is to be understood that the various change, substitutions,and alterations could be made hereto without departing from the spiritand scope of the invention.

What is claimed is:
 1. A multilayer ceramic capacitor comprising: amultilayer structure in which each of a plurality of ceramic dielectriclayers and each of a plurality of internal electrode layers arealternately stacked, wherein: (a current value at 10 V/μm when a directvoltage is applied to the plurality of the ceramic dielectric layers at125 degrees C.)/(a current value at 10 V/μm when a direct voltage isapplied to the plurality of the ceramic dielectric layers at 85 degreesC.) is more than 5 and less than 20; and a donor element concentrationin the plurality of ceramic dielectric layers is 0.05 atm % or more and0.3 atm % or less.
 2. The multilayer ceramic capacitor as claimed inclaim 1, wherein an average grain diameter of the plurality of ceramicdielectric layers is 80 nm or more and 200 nm or less.
 3. The multilayerceramic capacitor as claimed in claim 1, wherein the donor element is atleast one of V, Mo, Nb, La, W and Ta.
 4. The multilayer ceramiccapacitor as claimed in claim 2, wherein the donor element is at leastone of V, Mo, Nb, La, W and Ta.
 5. The multilayer ceramic capacitor asclaimed in claim 1, wherein a thickness of the plurality of ceramicdielectric layers is 1 μm or less.
 6. The multilayer ceramic capacitoras claimed in claim 1, where a main component ceramic of the pluralityof ceramic dielectric layers has a perovskite structure.
 7. Amanufacturing method of a multilayer ceramic capacitor comprising:forming a green sheet of which a concentration of a donor element withrespect to a main component ceramic is 0.05 atm % or more and 0.3 atm %or less; forming a multilayer structure by alternately stacking thegreen sheet and a conductive paste for forming an internal electrode;and baking the multilayer structure, wherein the multilayer structure issintered in the baking so that, in the multilayer structure after thebaking, (a current value at 10 V/μm when a direct voltage is applied tothe plurality of the ceramic dielectric layers at 125 degrees C.)/(acurrent value at 10 V/μm when a direct voltage is applied to theplurality of the ceramic dielectric layers at 85 degrees C.) becomesmore than 5 and less than
 20. 8. The method as claimed in claim 7,wherein in the forming of the green sheet, a green sheet of a maincomponent ceramic in which the donor element of 0.05 atm % or more and0.3 atm % or less is solid-solved in advance is formed.